There is often a need to determine the transmissive or reflective properties of an object. The color of a sample can be determined by measuring its transmittance or reflectance properties at different wavelengths. For example, it is known to measure light that has been reflected from or transmitted through an object at wavelengths from 400 nm to 700 nm, typically at 10 nm intervals. However, to obtain accurate measurements of the spectrum of an object, a color sensor must have sufficient wavelength channels. Sensors with many wavelength channels (typically 31) produce highly accurate measurements but have cost and complexity drawbacks. Conversely, a sensor with few wavelength channels is cheaper and easier to produce, but such sensors have lower measurement fidelity and produce a less accurate measurement compared to sensors with higher wavelength channels. Specifically, the measurement values obtained by a color measurement device that has a low numbers of wavelength channels will be less accurate compared to the measurement values obtained by a color measurement device having a greater number of wavelength values.
For example, a 6-channel spectral sensor, such as the AS7262, produced by AMS USA of Cupertino, Calif. USA, can be used to measure reflectance spectra. However, such devices are not currently able to obtain a full spectrum of reflectances in the range of 400˜700 nm with 10 nm intervals.
One mechanism to compensate for the lack of measurement fidelity is to use matrix transformation, such as described in commonly owned U.S. patent application Ser. No. 15/934,044, herein incorporated by reference in its entirety. As described therein, when using a low measurement fidelity measurement configuration, a series of known transmittance or reflectance color standards can be measured, and through the use of matrix transformation, a full transmittance or reflectance spectrum of the specimen can be recovered. However, using such matrix transformation can, at times, introduce measurement errors, noise or artifacts that yield a recovered spectrum having less than satisfactory results.
Thus, what is needed in the art is a system, method and computer implemented products that provide a color measurement system that includes noise reduction functionality and is less susceptible or sensitive to noise. In a further implementation, what is needed are approaches to maintaining or improving the stability of a color measurement system when using matrix-transformation approaches to recovering spectral information.
Furthermore, what is also needed is a solution to the problem introduced by using matrices to correct for inaccuracy of estimation of color values due to a low number of measurement channels.